Method of tempering glass



Janl`27, i B' METHOD oF 'rsursnrue V:mss

original Filed Dec. 17, 19:55

l PatentedJan. 27, 1942 UNITED STATES PATENT OFFICE METHOD OF TEMPERINGGLASS Bernard Long, Paris, France, assignor to The American SecuritCompany, Wilmington, Del., a company of Delaware Original applicationDecember 17, 1935, Serial No. 54,918, 110W Patent N0. 2,244,715, datedJune 10,

Divided and this application March 17,

1939, Serial No. 262,579. In France December y 2 Claims.

For some purposes it is desirable that a piece of glass instead of beingtempered throughout its area to a substantially equaLamount, be temperedunequally at different points, or, While tempered at one point or zgne,be without strainv at another. VAn example of "this is the windshieldsheet shown and claimed in my prior application, Serial No. 54,918, ledDecember 17, 1935, which application issued into Patent No. 2,244,715,on June 10, 1941, of` which application this is a division, and whichsheet consists of a plurality of `more or less circ-ular untemperedportions connected byareas of high temper. The aforesaid applicationdescribes several methods of producing such a windshield and thisapplication is directed to one of such methods which is characterized bythe initial tempering of areas which are to be ultimately non-tempered,and removing thestrain from such selected areas by a proper heattreatment.

Referring to the accompanying drawing in which corresponding parts aredesignated by corresponding marks of reference:

Figure 1 is `a sectional view of. a reheating structure adapted to carryout my improved method on a sheet of glass; Figure 2 is an elevation ofone of the refractory slabs shown in Figure 1;

Figure 3 is an elevation of one of the grills shown in Figure 1. f

.In carrying out my--method as applied to a windshield, a sheet oflglass c after having been tempered in any suitable 'known way. more orless uniformly, is placed ,between reheaters. Each of these consists ofa refractory slab I6 having mounted on the` inner face-thereof at pointsopposite those portions of the plate from which the temper is to beremoved, heating elements I5, preferably in the form of electrically 1heated resistance coils. Between the heating elements are located thevertical and horizontal bars of a grill' Work I1 which may be hollow forthe passage of the cooling fluid. The bars pro.- ject from the innerface of the slab and contact with the plate. Under these conditions heatfromthe elements I5 releases the strain in the i zones surrounding zoneswhich are tempered to.

a leeser degree which comprises tempering said portion of the sheet byheating and cooling suddenly, and subsequently reheatlng said portion ofthe sheet at the surrounded zones.

BERNARD LoNG.

